Book Image

Mastering React Test-Driven Development - Second Edition

By : Daniel Irvine
Book Image

Mastering React Test-Driven Development - Second Edition

By: Daniel Irvine

Overview of this book

Test-driven development (TDD) is a programming workflow that helps you build your apps by specifying behavior as automated tests. The TDD workflow future-proofs apps so that they can be modified without fear of breaking existing functionality. Another benefit of TDD is that it helps software development teams communicate their intentions more clearly, by way of test specifications. This book teaches you how to apply TDD when building React apps. You’ll create a sample app using the same React libraries and tools that professional React developers use, such as Jest, React Router, Redux, Relay (GraphQL), Cucumber, and Puppeteer. The TDD workflow is supported by various testing techniques and patterns, which are useful even if you’re not following the TDD process. This book covers these techniques by walking you through the creation of a component test framework. You’ll learn automated testing theory which will help you work with any of the test libraries that are in standard usage today, such as React Testing Library. This second edition has been revised with a stronger focus on concise code examples and has been fully updated for React 18. By the end of this TDD book, you’ll be able to use React, Redux, and GraphQL to develop robust web apps.
Table of Contents (26 chapters)
Part 1 – Exploring the TDD Workflow
Part 2 – Building Application Features
Part 3 – Interactivity
Part 4 – Behavior-Driven Development with Cucumber

Undoing and redoing user actions in Redux

In this section, we’ll add undo and redo buttons at the top of the page, which allow the user to undo and redo statements that they’ve previously run. They’ll work like this:

  1. Initially, both buttons will be disabled.
  2. Once the user executes a statement, the Undo button will become enabled.
  3. When the user clicks the Undo button, the last statement will be undone.
  4. At that point, the Redo button becomes available, and the user can choose to redo the last statement.
  5. Multiple actions can be undone and then redone, in sequence.
  6. If the user performs a new action while Redo is available, the redo sequence is cleared, and the Redo button becomes unavailable again.

Aside from adding button elements, the work involved here is building a new reducer, withUndoRedo, which will decorate the script reducer. This reducer will return the same state as the script reducer, but with two additional properties...